Pressure sensitive fluoran derivative copying paper



United States Patent 3,514,310 PRESSURE SENSITIVE FLUORAN DERIVATIVE COPYING PAPER Shiro Kimura, Teruo Kobayashi, and Sadao Ishige, Kanagawa, and Shizuo Katayama, Shizuoka, Japan, assignors to Fuji Photo Film Co., Ltd., Ashigara-Kamigun, Kauagawa, J apau No Drawing. Filed Nov. 16, 1967, Ser. No. 683,491 Claims priority, application Japan, Nov. 18, 1966, 41/75,936; Nov. 19, 1966, 41/76,038, 41/76,039 Int. Cl. B41c 1/06 US. Cl. 117-36.2 2 Claims ABSTRACT OF THE DISCLOSURE A pressure-sensitive transferring sheet, adapted to be used in conjunction with another sheet having an electron accepting layer, comprising a support and, coated on said support, a layer containing pressure-rupturable microcapsules, said microcapsules containing as a color former, at least one fiuoran derivative represented by the general formula:

wherein R represents a lower alkyl group,

when Y is a hydrogen atom, X is a radical selected from the group consisting of a lower alkyl group, a lower alkoxy group and a benzyloxy group,

when X is a hydrogen atom, Y is a radical selected from the group consisting of a chlorine atom, a lower alkyl group, a lower alkoxy group, a benzyloxy group, an acetoamino group, a N-acetyl-N-lower alkylamino group, and a N-acetyl-N-benzylamino group, and

when X is a methyl group, Y is a chlorine atom.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates generally to a pressuresensitive copying paper and more particularly it relates to a pressure-sensitive copying paper containing a fluoran derivative as a color former.

Description of the prior art Pressure-sensitive copying papers are usually composed of a transferring sheet, having thereon a layer of fine capsules containing therein a solution of an electron donating colorless organic compound (hereinafter the organic compound is called color former) in an oil, and a receiving sheet, having thereon a layer of electron accepting solid and a suitable binder. When both sheets are put together such that the electron donating layer is brought into contact with the electron accepting layer, and the piled sheets are pressed partially by handwriting or typewriting, the capsules at the pressed areas are ruptured and the colorless color former contained in the capsules is adsorbed on the solid acid to form a color. There have also been employed pressure-sensitive copying paper systems consisting of the aforesaid transferring 'ice sheet (hereinafter this sheet is called the upper sheet) and a receiving sheet (hereinafter this sheet is called the under sheet) and an intermediate sheet (hereinafter this sheet is called the middle sheet) having coated on the opposite surfaces a layer of microcapsules containing the color former solution and a layer of the solid acid and a binder.

As the electron accepting solid acid, there are known acid clay, attapulgite, zeolite, bentonite, kaolin and the like.

Also, as the electron donating color former, in particular, as a red color former, there are known Rhodamine Lactone, Rhodamine Anilinolactam and the like. However, the conventional red-color formers, for example, the lactonized products of Rhodamine B (Color Index (C.I.) No. 45,170, Rhodamine G (Cl No. 45,150) and Rhodamine GCP (C.I. No. 45,160)) have the fault that when they are placed in a normal ambient atmosphere, they are soon colored owing to the instability thereof. Hence, the upper sheet, having a layer of microcapsules containing such a conventional red-color former, tends to be colored or fogged before use. Further, although the anilinolactamized products of the aforesaid rhodamines are stable when they are stored for a long period of time, it takes several minutes to finish completely the coloring at the partially pressed areas of a pressuresensitive paper containing the color former. Also, since the color thus formed by the contact of the color former and a solid acid has a light absorption maximum near 550 m to 560 III/1., and has weak absorption in a range of from 560 m to 600 mg, the color is purplish red, which gives a dark feeling.

An object of this invention is to provide a pressure sensitive copying paper which is colored in red.

Another object of this invention is to provide pressuresensitive copying papers which can be colored in various colors by using known yellow-, purple-, and blue-color formers together with a fiuoran derivative shown by the general formula, as a red-color former.

SUMMARY OF THE INVENTION According to the present invention, there is provided a pressure-sensitive copying paper containing as a colorformer, a fiuoran derivative represented by the following general formula:

wherein R represents a lower alkyl group,

when Y is a hydrogen atom, X represents a group se selected from the group consisting of a lower alkyl group, a lower alkoxy group, and a benzyloxy group,

when X is a hydrogen atom Y represents a group selected from the class consisting of a chlorine atom, a lower alkyl group, a lower alkoxy group, a benzyloxy group, an acetoarnino group, a N-acetyl-N-lower alkylamino group, and a N-acetylN-benzylarnino group, and

when X is a lower alkyl group, Y represents a chlorine atom.

3 DETAILED DESCRIPTION OF THE INVENTION Typical examples of the color formers used in this invention are shown in the following table.

4 of 3-dimethylamino-7-methyl-fluoran having a melting point 197 C., was obtained (cf., Beilstein; Handbuch der Organischen Chemie; vol. 19, p. 350).

Color G eneral formula former N o. R X Y Name of compound 1 CzH H CH 3-diethylamino-7-methylfiuoran.

2 C 11 H Cl 7-chloro-3 diethylaminofluoran.

3 CZH5 CH Cl 7-chloro-3-diethylamino-6- methyLfiuoran.

4 CH H CH 3-dimethylamino-7-methylflnoran.

5 CH OCH3 H 3-dimethylamino-6-methoxyfiuoran.

6 CZHE CH3 H 3-diethylamino-G-methoxyfluoran.

7 C2H5 0 0211 H 3-diethylamino-6- ethoxyfiuoran.

8 C 211 H O 0 H 3-diethylamino-7-methoxyfiuoran.

9 C2H5 O C H2O 6H5 H 3-diethylammo-6-b enzyloxyfiuoran.

10 CzH H O CHzC 5H5 3-dieth ylamino-7-b enzyloxyfiuoran.

11 C211 H N HO OCH; 7-afioetamino-3-diethy1aminouo ran.

12 CzH5 H N (CH3) C 0 CH3 7-N-acetyl-N-methylamino- 3-diethylamino-fluoran.

13 CzHs H N (CH2CuH5) C 0 CH 7-N-acetyl-N-benzylamino-3- diethylamino-fiuoran.

14 CH H N HC OCH3 7-acetamino-3-dimethylamino-fluoran.

15 CH3 H N (CzHs) C OCH 7-N-acetyl-N-ethylamino-3- dimethylamino-fiuoran.

Practical examples of preparing the above color formers are shown below, in which Beilstein refers to Beilsteins Handbuch der Organischen Chemie.

PREPARATION 1 (Preparation of Color Former No. 1)

Into about 180 g. of concentrated sulfuric acid were dissolved 0.1 mol of 2-carboxy-4-diethylamino 2 hydroxybenzophenone (cf., -Beilstein; Handbuch der Organischen Chemie; vol. 14, page 675; ibid.; vol. 14, Supplement 1, p. 710; and J. American Chemical Society; vol. 38, p. 2102) and 0.1 mol of p-cresol, and the resulting solution was heated for 3 hours to 90-100 C. After cooling the reaction solution, it was poured into ice water to provide a precipitate, which was neutralized by aqueous ammonia or aqueous sodium carbonate solution and then extracted with chloroform. The extract was washed with water several times and concentrated under a reduced pressure to provide a crude crystal. By recrystallizing the crude crystal from a mixed solvent of benzene and petroleum ether, 27 g. of the white crystal of 3-diethylamino-7-methyl-fluoran having a melting point of 135 C., was obtained.

PREPARATION 2 (Preparation of Color Former No. 2)

By repeating the same procedure as in Preparation 1 while using p-chlorophenol instead of p-cresol, 33 g. of the White crystal of 7-chlor0-B-diethylamino-fluoran having a melting point of 173-174 C., was obtained.

PREPARATION 3 (Preparation of Color Former No. 3)

By repeating the same procedure as in Preparation 1 while using 4-chloro-3-methyl-phenol instead of p-cresol, 31.9 g. of the white crystal of 7-chloro-3-diethylamino- 6-methyl-fiuoran having a melting point of 237239 C., was obtained.

PREPARATION 4 (Preparation of Color Former No. 4)

By treating 0.1 mol of 2'-carboxy-4-dimethylamino-2- hydroxybenzophenone (Beilstein; Handbuch der Organischen Chemie; vol. 14, p. 675 and ibid., Supplement 1, p. 710) and 0.1 mol of p-cresol in concentrated sulfuric acid as in Preparation 1, g. of the white crystal PREPARATION 5 (Preparation of Color Former N0. 5)

Into 3 0 ml. of concentrated sulfuric acid were dissolved 9.5 g. of 2'-carboxy-4-dimethylamino-2-hydroxybenzophenone and 5.5 g. (about 1.2 times of the theoretical amount) of resolcindimethyl ether, and the resulting solution was maintained for 48 hours at room temperature. Then, the solution was heated for one hour to 80 C., and after cooling, was poured into ice water. A pre- .cipitate thus formed was obtained by filtration, neutralized with aqueous ammonia and extracted with chloroform. The extract was washed with water several times and concentrated under a reduced pressure to provide a syruppy product. By recrystallizing the product from a benzene-ether mixed solution, 8.7 g. of the crystal of 3- dimethylamino-6-methoxy-fluoran having a melting point of 167169 C., was obtained (Beilstein; vol. 19, p. 356).

PREPARATION 6 (Preparation of Color Former No. 6)

The above example was repeated while using 2-carboxy-4-diethylamino-2 hydroxybenzophenone (hereinafter, it is called intermediate A) and the crystal of 3- diethylamino-6-methoxy fluoran having a melting point of 222 C., was obtained. Moreover, the same compound was obtained by methylating 3-diethylamino-6-hydroxyfiuoran (-Beilstein; vol. 19, p. 356) with dimethyl sulfate and an alkali (Beilstein; vol. 19, p. 357).

PREPARATION 7 (Preparation of Color Former No. 7)

By repeating the same procedure as Preparation 5 while using intermediate A and resorcindiethyl ether, the crystal of 3-diethylamino-6-ethoxy-flu0ran was obtained. Further, the same compound was obtained with diethyl sulfate as in Preparation 6.

PREPARATION 8 (Preparation of Color Former No. 8)

By condensing intermediate A and an equimole of hydroquinone dimethyl ether in sulfuric acid as in Preparation 5, the crystal of 3-diethylamino-7-methoxyfluoran having a melting point of 129-130 C., was obtained.

PREPARATION 9 (Preparation of Color Former No. 9)

By treating intermediate A and an equimole of resorcindibenzyl ether in sulfuric acid in Preparation 5, the crystal of 3-dimethylamino-6-benzyloxy-fiuoran was obtained. Further, the same compound was obtained by benzylating 3-diethylamino-6-hydroxy-fluoran with benzyl chloride under the presence of an alkali.

PREPARATION 10 (Preparation of Color Former No. 10)

By treating intermediate A and hydroquinone dibenzyl ether in sulfuric acid as in Preparation 5, the crystal of 3-dimethylamino-7-benzyloxy-fluoran was obtained. Further, the same compound was obtained by condensing intermediate A and hydroquinone in 50% sulfuric acid at 140 C. (Beilstein; vol. 19, p. 355).

PREPARATION 11 (Preparation of Color Former No. 11)

Into about 180 g. of concentrated sulfuric acid were dissolved 0.1 mol of intermediate A and 0.1 mol of 4- acetaminoanisole or 4-acetaminophenet0le or 4-acetaminophenol, and the resulting solution was maintained for about 40 hours at -30" C. The solution was then poured into ice water to form a precipitate, and which was filtrated. The precipitate thus obtained was neutralized by aqueous ammonia or aqueous sodium carbonate solution and then extracted with chloroform. After washing with water several times, the extract was concentrated under a reduced pressure to provide a syrupy product which was dissolved into a mixed solvent of benzene and ether. This solution was allowed to cool to provide a white crystal of 7-acetamino-3-diethylaminofiuoran having a melting point of 142-l43 C., with a yield of about 60%.

PREPARATION 12 (Preparation of Color Former No. 12)

The same procedure as in Preparation 11 was repeated using intermediate A and 4-N-acetyl-N-methylaminoanisole or -phenetole or -phenol and a white crystal of 7-N-acetyLN-methylamino-3-diethylamino fluoran having a melting point of 132-133 C., was obtained.

PREPARATION 13 (Preparation of Color Former No. 13)

The same procedure as in Preparation 11 was repeated using intermediate A and 4-N-acetylN-benzylaminoanisole or -phenetole or -phenol and 7-N-acetyl-N-benzylamino-3-diethylamino-fluoran was obtained.

PREPARATION 14 (Preparation of Color Former No. 14)

The same procedure as in Preparation 11 was repeated using 2 carboxy 4 dirnethylamino 2 hydroxybenzophenone and 4-acetamino-anisole or -phenetole or -phenol and 7-acetamino-3-dimethylamino-fiuoran was obtained.

PREPARATION 15 (Preparation of Color Former No. 15)

The same procedure as in Preparation 11 was repeated using 2 carboxy 4 dimethylamino 2 hydroxybenzophenone and 4-N-acetyl-N-ethylarnino-anisole or -phenetole or -phenol and 7-N-acetyl-N-ethylamino-3-dimethylamino-fluoran was obtained.

Each of the color formers No. 1 to No. 15, thus prepared, was dissolved in 95% acetic acid to cause red coloring and the absorption spectra of the red-colored solutions were measured. Their absorption maxima are shown in the following table.

Color Absorption 2nd absorption 3rd absorption former No. maximum (mu) maximum (my) maximum (mu) In order to prepare the pressure-sensitive copying paper of this invention using the color former mentioned above, there may be employed any known methods, for example, the methods disclosed in U.S. Pats. 2,548,366; 2,800,457 and 2,800,458 in which microcapsules containing color former are produced by utilizing a so-called composite coacervation.

The pressure-sensitive copying paper of this invention contains as a color former the compound represented by the aforesaid general former and the properties of the pressure-sensitive copying paper are not influenced by the manner employed for preparing it. Therefore, there are no limitations on the method of producing the pressuresensitive copying papers of this invention.

The amount of the color former is usually 15% by weight based on the weight of the oily solvent.

The pressure-sensitive copying paper of this invention is colorless before use and is stable and forms no color fog when placed in atmosphere for a long period of time. When the pressure-sensitive copying paper is pressed partially by handwriting or typewriting, coloring occurs instantly. Moreover, since the color thus formed effectively absorbs light in the range of from about 470 m to about 550 mm, the red color thus formed is brighter than that obtained by conventional pressure-sensitive copying papers, the color density is high, and the light resistance and water resistance thereof are excellent.

Furthermore, by using the aforesaid color former of this invention together with known yellow-color formers, purple-color formers, blue-color formers, bluish greencolor formers, and the like, a pressure-sensitive copying paper capable of providing deep-black copying can be obtained without being accompanied by any bad influences, such as, desensitization.

The invention is further explained by the following examples:

EXAMPLE 1 Into g. of diphenyl chloride was dissolved 3 g. of color former No. 1 and the solution was emulsified by mixing with a solution of 20 g. of gum arabic in g.-

of water. Then, a solution of 29 g. of acid treated gelatin in 160 g. of water was added to the resulting emulsion, acetic acid was added to the mixture while stirring to reduce the pH thereof to 5, and 500 g. of water was added to the system to cause coacervation, whereby the oil drops containing the color former were covered by liquid films of a concentrated solution of gelatin and gum arabic. Thereafter, the pH of the system was further reduced up to 4.4 and then 4 g. of 37% formalin was added thereto for hardening. During the aforesaid procedure, the system was maintained at a temperature of 50 C. Thereafter, the temperature of the system was reduced to 10 C., to gel the films of the concentrated liquid and also the pH was increased to 9 for increasing the hardening effect of the films. The system was allowed to stand in these conditions for several hours to finish the capsulation. The coating composition containing the microcapsules thus prepared was applied to a paper by a conventional coating manner such as roller coating or air-knife coating and the like and dried to 7 provide an upper sheet. When the upper sheet thus prepared was placed on a clay paper or on the under sheet (having a clay-containing layer) and then the assembly was pressed partially by handwriting, a red copy was instantly formed on the clay paper. The thus formed red color did not fade when it was wet with water and directly exposed to sunlight for a long period of time. Also, when the upper sheet having the layer containing the color former was heated for hours to 100 C., and also exposed to sunlight for a long period of time, the color forming property of the color former was not reduced. In other words, the pressure-sensitive copying paper of this invention had suflicient light resistance, water resistance and heat resistance both before and after color forming.

EXAMPLE 2 The same procedure as in Example 1 was repeated while using color formers No. 2 to N0. 15 respectively instead of color former N0. 1. In each case, red copy was formed rapidly on a clay paper. The properties of the color former of the pressure-sensitive papers thus prepared were almost the same as those in Example 1.

EXAMPLE 3 The absorption maxima of the red-colored color formers on a clay paper having an acid clay layer were measured. The results are shown in the following table.

Color Absorption 2nd absorption 3rd absorption former No. maximum (m maximum (my) maximum (my) EXAMPLE 4 The same procedure as in Example 1 was repeated while using instead of color former No. 1 a mixed color former system of 0.9 g. of red-color former No. 1, 0.6 g. of benzoylleucomethylene blue, 0.7 g. of Malachite Green Lactone, 0.4 g. of N-phenylleuco Auramine (said three color formers are all blue-color formers), 0.8 g. of Crystal Violet Lactone (Bluish purple color former), and 1.2 g. of 3,6-diethoxyfluoran (yellow-color former). As a result, a black copy was instantly formed on the copy paper.

Further, almost the same results were obtained by using color formers No. 2 to No. 15, instead of color former No. 1, in the above example.

What is claimed is:

1. A pressure-sensitive transferring sheet, adapted to be used in conjunction with another sheet having an electron accepting layer, comprising a support and, coated on said support, a layer containing pressure-rupturable microcapsules, said microcapsules containing oil and dissolved therein a color former comprising at least one fluoran derivative represented by the general formula:

wherein R represents a lower alkyl group,

when Y is a hydrogen atom, X is a radical selected from the group consisting of a lower alkyl group, a lower alkoxy group and a benzyloxy group,

when X is a hydrogen atom, Y is a radical selected from the group consisting of a chlorine atom, a lower alkyl group, a lower alkoxy group, a benzyloxy group, an acetoamino group, a N-acetyl-N- lower alkylamino group, and a N-acetyl-N-benzylamino group, and

when X is a methyl group, Y is a chlorine atom.

2. The pressure-sensitive copying paper according to claim 1 wherein said color former is selected from the group consisting of 3-diethylamino-7-methyl-fiuoran, 7- chloro-3-diethylamino-fluoran, 7-chloro-3-diethylamino-6- methyl-fluoran, 3 dimethylamino-7-methyl-fluoran, 3-dimethylamino 6 methoxy-fluoran, 3 diethylamino-6- rnethoxy-fluoran, 3-diethylamino-6 ethoxy-fiuoran, 3-diethylamino-7-methoxy-fiuoran, 3-diethylarnino 6-benzyloxy-fluoran, 3-diethylamino-7-benzyloxy fluoran, 7-acet amino-3-diethylamino-fiuoran, 7 N acetyl-N-methylamino-3-diethylamino-fluoran, 7-N-acetyl-N-benzylamino- 3-diethylarnino-fluoran, 7-acetamino 3 dimethylaminofluoran, and 7-N-acetyl-N-ethylamino-3 dimethylaminofluoran.

References Cited UNITED STATES PATENTS 3,020,171 2/1962 Bakan et a1. 11736.2 3,244,550 4/1966 Farnham et al 11736.2 3,336,337 8/1967 Gosnell 117-361 3,427,180 2/1969 Phillips 117-36.2

MURRAY KATZ, Primary Examiner US. Cl. X.R. 

